Nowadays everyone thinks that saturated fats are bad for you and can cause heart disease; and that polyunsaturated oils are good for us. Long time ago people used to cook with butter, lard, coconut oil and olive oil, which are either saturated or monounsaturated. Today, most of the fats in modern diet are polyunsaturated from vegetable oils derived mostly from corn, soy, sunflower and canola.
Despite of consuming these supposedly "healthy" oil, what happens to the health of the public? Heart disease cases always go up, people are getting fatter and fatter and more people are obese.
These "supposedly healthy" oil contain a preponderance of polyunsaturated fatty acids. Two polyunsaturated fatty acids found most frequently in our food are omega-6 and omega-3. They are also called "essential fatty acids" because our body cannot make them and we need them.
These fatty acids are highly reactive, especially the important omega-3 (which is necessary for cell oxidation, for metabolizing important sulphur-containing amino acids and for maintaining proper balance in prostaglandin production).
During the process of extracting these modern commercial vegetable oils, omega-3 tends to break apart. So what's left is mostly omega-6. And research has revealed that too much omega-6 in the diet creates an imbalance that can interfere with production of important prostaglandins. This disruption can result in increased tendency to form blood clots, inflammation, high blood pressure, irritation of the digestive tract, depressed immune function, sterility, cell proliferation, cancer and weight gain.
What's worse: The extraction process of these vegetable oils. In modern factories, these oils are obtained by crushing the oil-bearing seeds and heating them to very high temperature. The oil is then squeezed out very high pressure, thereby generating more heat. During this process, these oils are exposed to damaging light and oxygen. In order to extract the last 10% or so of the oil from crushed seeds, processors treat the pulp with one of a number of solvents—usually hexane. The solvent is then boiled off, although up to 100 parts per million may remain in the oil. Such solvents, themselves toxic, also retain the toxic pesticides adhering to seeds and grains before processing begins.
As mentioned earlier, omega-3 tends to break apart due to the heat, thereby creating free radicals - that is, single atoms or clusters with an unpaired electron in an outer orbit. These compounds are extremely reactive chemically and they attack cell membranes and red blood cells, and cause damage in DNA/RNA strands, thus triggering mutations in tissue, blood vessels and skin. Free radical damage to the skin causes wrinkles and premature aging; free radical damage to the tissues and organs sets the stage for tumors; free radical damage in the blood vessels initiates the buildup of plaque.
In addition, antioxidants, such as fat-soluble vitamin E, which protect the body from the ravages of free radicals, are either neutralized or destroyed by high temperatures and pressures. BHT and BHA, both suspected of causing cancer and brain damage, are often
added to these oils to replace vitamin E and other natural preservatives destroyed by the extraction process.
With all being said about these processed commercial vegetable oils, almost all nuts and seeds are, however, still great sources of natural unprocessed healthy fats. Eating them fresh and unprocessed is good for you because they are some of the healthiest fatty foods. And if you are lucky enough to find cold-pressed versions of these oil that made from nuts or seeds, use them for salad dressing or spread. DON'T USE THEM FOR COOKING - for good reasons.
More reading here.
